Dynamoelectric machine



June 28, 1949. E. A. BINNEY 2,474,648

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ATTORNEY Patented June 28, 1949 DYNAMOELECTRIC MACHINE Eric AltonBinney, Ilkley, England, assignor to The English Electric CompanyLimited, London, England, a British company Application February 24,1945, Serial No. 559,584 In Great Britain February 24, 1944 13 Claims.(Cl. 32263") This invention concerns direct-current dynamoelectricmachines of the amplifying type and is related to the invention of mycope-riding application Serial No. 5,098, filed January 29, 1948.

One type of dynamo-electric amplifier is excited by armature reaction,there being a pair of cross connected brushes between the normalcommutator brushes of the machine and such a machine has the advantageof rapid response to the controlling current or voltage. An object ofthe present invention is to enable a quick response to be obtained witha normal type of machine as an alternative to the armature reaction typeof machine, although the invention can be come 'bined with a machine ofthe latter type.

According to the invention, a direct-current dynamo-electric machine hasan armature, a self-excited field winding and a separately excited orcontrolling field Winding to which can be applied an excitationdependent on the magnitude which is to be amplified, these two fieldwindings having no appreciable mutual inductance, i. e. there issubstantially no magnetic coupling or no appreciable magnetic couplingbetween the two field windings.

The invention is illustrated by the accompanying drawings, in which:

Fig. 1 is a schematic and part-sectional axial view of .one form of theinvention,

Figs. 2 and 8 are two more realistic views from opposite ends of thesame machine,

Fig. 4 is a view of a modified embodiment, and

Figs. 5 to 15 show various ways of connecting the windings of a machineaccording to Figs. 1 to 3, or Fig. 4.

According to Fig. 1, the machine represented by Figs. 1 to 3, has afield structure I and an armature Ill. The armature has two systems 'ofarmature windings, shown schematically and denoted by 2 and 3. Armaturewindings 2 are Wound for a two-pole (rt-pole) system, while armaturewindings 3 are wound for a f our-pole (m pole) system. The armature hasa commutator l i for winding 2 with appertaining collector brushes l2(Fig. 3). A second commutator i3 is connected with the winding 3 and hasbrushes M (Fig. 2). The field structure I four pole pieces I5, l6, l1and it which carry a two pole (71-13016) field winding I 9 and. afour-pole (mpole.) field winding 20. The field winding i9 is aseparate-excitation winding and connected to terminal T. The fieldwinding 20 is self-excited and connectedto brushes [2. The brushes M areThe two armature connected to terminals T2. windings can occupy the samearmature slots,

one being placed over the other. The commutators may conveniently be.placed at opposite ends of the armature as shown.

It, at the speed which the machine is rotated, the field winding 2.0 isjust insufficientwhen unaided-to cause the machine to generate, then theapplication to terminals Tl' of field winding IQ of an electro-rnotiveforce (E. M. F.) dependent on. the magnitude which is to be amplifiedwill increase the total excitation suiiiciently to enable the armatureHi to energize the winding 29 and so produce an E. M. F. in the armaturel0 (and a voltage across the output terminals T2 connected to thebrushes I4) which is substantially proportional to and a considerableamplification of the E. M. F. applied to winding Hi. Thisproportionality exists so long as the flux paths are unsaturated,because under that condition the build-up of. current in field winding20 will have substantially no reaction on the field winding 59.Consequently the voltage across terminals T2 will respond promptly tochanges in the voltage applied to. terminals Tl. More in detail, thewinding l9 wound around polepieces l5 and IE to make them both, forexample, north poles and around poles l1 and I8 to make them both, forexample, south poles, will produce a 2-p0le magnetic field which willhave no appreciable eifect on the armature winding connected tocommutator 13 while the four pole winding 20 around pole pieces l5 to T8making them north, south, north, south poles respectively will have noappreciable elfect on the armature winding connected to commutator H.

Fig. 4, which is a modification of Fig. 3, shows the field system havingone pole structure divided into parts [5a and Ilia and another polestructure divided into parts Na and I 8a. The 4-p01e field winding iswound around eachof these parts separately. The 2-pole field winding hascoils embracing parts 15a and Mia as a whole, to form one pole, andcoils embracing parts Ila and lfla to form the other pole. Figs. 2, 3and 4 also show interpoles 4-1 with coils thereon, which may beconnected in conventional manner in series with the respective armaturewindings for the purpose of satisfactory commutation.

In Fig. 5 the 2-pole field winding is represented at Li and connected toterminals Tl; the 4-pole field winding is represented at 20 andconnectedacross the brushes l2. If now a voltage propor tional to themagnitude to be amplifiedbe appliedto terminals Tl of the 2-pole fieldwinding l9, which thus acts as the control winding, the 2-po-le field:produced will notinduce an E; M. F. in the 3 armature winding connectedto commutator l3, nor will the application of this E. M. F. to the2-pole field winding I!) have any appreciable inductive effect on the-pole field winding 26. The E. M. F. induced in the armature windingconnected to commutator II will energize the 4- p'ole field winding 20through commutator i i and brushes l2; the -pole field will induce an E.M. F. in the armature winding connected to commutator l3 without havingany action on either the Z-pole armature winding or the 2-pole fieldwinding. The 4--pole armature winding will consequently yield, acrossthe brushes l4 and terminals T2 connected thereto a highly amplified E.M. F. substantially proportional to that applied to the 2-pole fieldwinding and the device will be comparatively quick in response. Again,the proportionality exists so long as the fiux paths are unsaturated.

The rate of response can be adjustably reduced by the damping fieldwinding 24 shown in Fig. 5, which is magnetically coupled with the 4-pole field winding 20 and has its circuit closed through the adjustableresistance 25 or additionally or alternatively through the adjustablecondenser 21. If this damping action is desired only in one sense, therectifying valve 25 is included in the circuit of resistance 25, or if aseparately adjustable damping action be required in the reverse sense afurther adjustable resist- 'ance 25a and a rectifier 26a connected inthe opposite sense to rectifier 26 are connected in shunt to resistance25 and rectifier 26.

The amplification can be increased in various ways. Fig. 6, for example,shows a two-pole compounding field winding 2! in series with the circuitof brushes l2 and field winding 20. Fig. 7 shows another way ofachieving the same result as Fig. 6. The circuit of winding I!) includesan adjustable part of the resistance 22 which is in the circuit ofbrushes l2 and field winding 26]; thus there is injected into thecircuit of winding l9 an E. M. F. proportional to the voltage acrossbrushes [2.

Fig. 8 shows the control winding as two separate windings [9a and lSbwhich can be supplied from two different sources which can be connectedto terminals T! and T3, if the machine be desired to act as adifferential or additive exciter. In this case the circuit of windingl9b includes the adjustable part of the resistance 22 which is in thecircuit of brushes l2 and field winding 26; thus there is injected intothe circuit of winding lSb an E. M. F. proportional to the voltageacross brushes I2. Fig. 9 shows another modification of the connectionswherein the sections [9a and l9b of the control winding are connected asopposite arms of a bridge of which the other arms are the resistors 28and 29. One pair of opposite corners of this is connected to theterminals T! and the other pair to the terminals T3 so that the controlfield can be energized in accordance with the sum or difference of thevoltages of two sources by connecting them to these terminals.

Fig. shows another way of increasing the amplification by the addition.of the compounding field winding 30 assisting the Z-pole control windingit) and connected in series with resistor 3! across the Z-nole armaturewinding through commutator H and brushes l2. Alternatively oradditionally the amplification may be increased by the field winding 32assisting the -pole field winding 21! and connected in series with theresistor 33 across the 4-pole armature winding switch 35 which has twocontacts in series with winding Hi. When the machine is to bedeenergized, the control field winding is is switched on by movement ofthe switch 35 from the position in which it is shown to the oppositeposition, thereby connecting up the winding 34 which acts as a so calledsuicide winding to eliminate residual magnetism in the field system.

In the winding arrangements so far described the z-pole field winding isthe controlling winding and the output is derived from the 4-polearmature winding. Fig. 12 shows the 2-pole field winding is connected inseries with a e-pole winding 23 across the brushes M; the controlling E.M. F. can be applied to the terminals Ti across which the ll-pole fieldwinding Z l is connected, and an amplified output proportional to thecontrolling E. M. F. can be derived from the 2-pole armature windingacross the brushes 12 through terminals T2.

Fig. 13 shows a modification of Fig. 12 in which the machine can be usedas a motor if the power supply is to the terminals T2 and so to brushesIE through the 2-po1e series field 39; the controlling field winding 29is supplied from the source at through the rheostat 3'1 and serves tocontrol the speed while requiring only a small amount of power fromsource 36. If the speed of the machine is to be automatically maintainedat approximately a constant value, the rheostat iil' may be actuated bythe speed governor 38 as indicated in 13. The arrangement according toFig. 5 could also be used as a motor by supplying power to terminals T2.

In Fig. 14 the commutator H is provided not only with the brushes l2,but also with a pair of brushes 4E1 displaced at electrical degrees fromthe brushes l2 and electrically connected together. In addition to the2-pole controlling field winding it connected to terminals Tl, there isthe 2- pole compensating field winding 41 on the axis of and connectedacross the brushes l2 in series with the ei-pole field winding 20. Thecompensating field winding is wound to reduce the effect of armaturereaction in the control field of winding is. In this arrangement, therewill be an initial stage of amplification, making, in all, three stagesof amplification in the machine. The rate of response may be adjusted bythe 2-pole field winding 42 on the axis of brushes 40 and having itscircuit closed through the adjustable rheostat 43.

If with the arrangement shown in Fig. 8 or Fig. 9 a steady biassingvoltage be applied across the terminals T3 a steady mean output voltagecan be derived from the machine while the E. M. F. applied to terminalsTI is zero. If an E. M. F. be applied to terminals Tl in one sense oranother the output voltage will rise above or fall below the mean valueby an amount which is an amplification of the applied voltage. Analternative method of achieving this result is shown in Fig. 15 whereina steady adjustable voltage is applied from the source 45 through theadjustable resistance M5 to the i-pole field winding 44 whichaccordingly produces a steady mean voltage across brushes I l andterminals T2 when no E. M. F.

tore so as tov causeg-l-when the: machine is open atod: asageneratorfia. voltage to. be generated be ween a: first. group ofsaidrbrushes, self-excite tion; field windingsunder control :bysaidvoltage and: disposed: on said. field; structure so astocausefiduringngenerator operationr a-nother volt. age to be generatedbetween another group of: said brushes, and an. external circuitconnected to said other group of brushes. I

2. A rotary 'direct'current machine, comprising a, normally unsaturatedmagnetic; circuit, including a multipolar field structure-and: anarmflzturei, said armature having two sets of windings and tworespective commutators therefor, each of said commutators having a setof brushes, self-excites tion; field windings disposed on said field;structure and controlled by curnent flowing. between the brushes :of oneof said set of brushes,,a sepa ate-excitation field winding disposed onsaid field structure for controlling said current, and circuitleads-attached to saidother set of brushes to-carr-y current controlledby saidwself-exczitaticn field winding.

3. A rotary direct current machine, comprising a normally unsaturatedmagnetic circuit including a multipolar field structure and an armature,said field structure having a separateexcitation field winding of afirst number of poles and a self-excitation field winding of a secondand larger number of poles, said armatures having two sets of windingsand two appertaining commutators correlated to said two field windingsrespectively, and said self -excitation field windings being connectedto said commutator correlated to said separate-excitation field winding.

4. A direct-current dynamo-electric machine, comprising a normallyunsaturated magnetic circuit having a multipolar field structure and anarmature, commutating means having a plurality of sets of brushes toestablish a corresponding plurality of separate circuits through saidarmature, a separate-excitation field winding disposed on said structureto generate a first voltage across the brushes of one of said sets, aself-excitation field winding disposed on said structure and controlledby current due to said first voltage for generating a second voltagebetween the brushes of said other set, said self-excitation fieldwinding being rated to be just-insufficient for generating said secondvoltage when said armature is running at normal speed while saidseparateexcitation winding is unexcited.

5. A direct-current dynamo-electric machine, comprising a normallyunsaturated magnetic circuit having a multipolar field structure and anarmature, said armature having two sets of windings and two respectivecommutators therefor, each of said commutators having a set of brushes,self-excitation field windings disposed on said field structure andcontrolled by current flowing between the brushes of one of said set ofbrushes, a, separate-excitation field winding disposed on said field:structure for: controlling said current,- said two fieldiwind-ings,being,.-substantially nona muctive relative to. each other- 6'. A dimecurrent. -.dyn:amoelectric machine, comprisiogza normally unsaturatedmagnetic cir-., cuit haying a; Inultipolar field structure and anmature; aidarmaturehaviug two commutators.

ngwa. second voltagebetween the brushes of said:

Qthetw et, said twofi-eld windings being substantially nongi-nductiverelative to each other, and said; seL-frexcitation field winding being:rated to be; just-insufiicient for generating said second voltage whensaid armature :is running at normal;

speedwhilesaid separate-excitation windingv is unoxcited.

7. A direct-current dynamo-electric machine, comprising av magneticfield system, an m-ipole ficldwindingaud an n-DOlefield winding thereon,where m/n. isanv even, number, said; two windings h ving no appreciablemutual inductance, an a mature associated: with said field system andcommon. to; saidv two fieldi windings, an. fin-112016 winding and ann-pole windin disposed on said armature, afinst commutator connected tosaid n-pole armat re Winding, a second commutator connected to saidm-pole armature winding, -r.e-, spective sets of collecting brushes onsaid com. imitators, one or saidfield windings being excited undercontrol by current flowing between brushes of one of said sets, inputleads connected to said other field winding, and output leads connectedto said other set of brushes.

8. A direct-current dynamo-electric machine, comprising a magnetic fieldsystem, an m-pole field winding and an n-pole field winding thereon,where m/n is an even number, an armature associated with said fieldsystem and common to said two field windings, said armature having anm-pole winding and an n-pole winding and two sets of commutator brushesfor said respective armature windings, said m-pole field winding beingconnected by one of said sets of brushes across said n-pole armaturewinding, another npole field winding being disposed on said field systemand being connected in circuit with said m-pole field windingj circuitmeans connected to said first n-pole field winding to apply excitationthereto, and circuit means connected to said other set of brushes toderive amplified energy therefrom.

9. With a machine according to claim 8, in combination, a damping fieldwinding disposed on said field system and inductively coupled with oneof said other field windings, and a variable impedance device inclosed-circuit connection with said damping field winding.

10. A machine according to claim 8, wherein an additional self-excitingfield winding is disposed on said field system, connected across one ofsaid armature windings, and wound for the same number of poles as thearmature winding across which it is connected.

11. A direct-current dynamo-electric machine, comprising a magneticfield system, an m-pole field winding and an n-pole field windingthereon, where m/n is an even number, an armature associated with saidfield system and common to said two field windings an m-pole winding andan n-pole Winding disposed on said armature, a first commutatorconnected to said n-pole armature winding, a second commutator connectedto said m-pole armature winding, circuit means connected to said n-polefield winding to supply input energy thereto, a first pair of brushesassociated with the commutator of said n-pole armature winding andarranged to provide a voltage drop generated under control by saidn-pole field winding, a cross-connection between the brushes of saidfirst pair to provide armaturereaction excitation, a second pair ofbrushes as-. sociated with said latter commutator and displacedsubstantially 90 electric degrees from said first pair of brushes todevelop an amplified voltage between the brushes of said second pairunder control by said armature-reaction excitation, said m-pole fieldwinding being connected to said second pair of brushes to be excited bysaid amplified voltage, and a set of brushes associated with said othercommutator to derive a further amplified voltage therefrom under controlby said m-pole field winding.

12. A machine according to claim 11., wherein an n-pole compensatingfield winding is disposed on said field system and connected in seriesWith said m-pole field winding, said compensating field winding beingwound to reduce the weakening effect of armature reaction on saidinput-energy excited n-pole field winding.

13. A direct-current dynamo-electric machine, comprising a normallyunsaturated magnetic circuit having a four-pole field structure and anarmature, a four-pole field winding and a twopole field winding disposedon said structure, said armature having correspondingly a four-polearmature winding and a two-pole armature winding and two appertainingcommutators, the com mutator appertaining to said two-pole armaturewinding havin a first pair of brushes arranged to provide a firstvoltage under control by said two-pole field winding, a cross-connectionbetween the brushes of said first pair to provide armature-reactionexcitation, a second pair of brushes associated with said lattercommutator and displaced substantially electric degrees from said firstpair of brushes to develop an amplified voltage between the brushes ofsaid second pair under control by said armature-reaction excitation,said four-pole field winding being connected to said second pair ofbrushes to be excited by said amplified voltage, and a set of brushesassociated with said other commutator to derive a further amplifiedvoltage therefrom under control by said four-pole field winding. ERICALTON BINNEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,255,400 Ferris Feb. 5, 19181,468,157 I-Iolifield Sept. 18, 1923 2,000,699 Harding May 7, 19352,018,107 Allen Oct. 22. 1935 2,060,244 Roe Nov. 10, 1936 2,094,492Pestarini s Sept. 28, 1937 2,183,397 Grundschneider Dec. 12, 1939

